multiplying fractions?

[Shaftsbury1]

hello could anyone please help me with this fraction problem?
1 2/3 * 3 5/7=
i have completely forgotten what the method is and my ds has not covered it at school yet. i think (and according to dh) you multiply denominators and numerators with each other?
also does anyone know whether this type of problem comes up in 11
plus in surrey.
thanks

[essex-mum18]

1 2/3 times 3 5/7

Change the mixed fractions into improper fractions first i.e. 1 2/3 = 5/3, 3 5/7 = 26/7

1 2/3 * 3 5/7

= 5/3 * 26/7

= 130/21 ( 6 4/21)

[rosered100]

hello could anyone please help me with this fraction problem?
1 2/3 * 3 5/7=
i have completely forgotten what the method is and my ds has not covered it at school yet. i think (and according to dh) you multiply denominators and numerators with each other?
also does anyone know whether this type of problem comes up in 11
plus in surrey.
thanks

Convert your sum into 5/3 * 26/7 =
then you can multiply as your DH says -
5*26 = 130
3*7 = 21

so 130/21 = 6 4/21

I dont know if it comes up in Surrey but havent seen that type of q in any papers we have tried. More likely to be something like 1/3 * 1/4 as that would have been covered in school I think

rosered

[rosered100]

Oooh - took too long to write the post!

[WP]

Although it doesn't come up in this example, fractions must always be reduced to the simplest form (by dividing by common factors) for full marks. It's a good idea to divide before multiplying, as then you're multiplying smaller numbers (and not dividing big numbers). e.g.

Code: Select all

                 21   15   21 x 15   3 x 3   9
2 1/10 x 2 1/7 = -- x -- = ------- = ----- = - = 4 1/2
                 10   7    10 x 7    2 x 1   2

edit: removed mention of cancelling

[Shaftsbury1]

thank you everyone for your help. i am sorry i am a bit late in responding!
And thank you for the tip on simplifying.
i did think this was an unusual q for 11+ as it is multiplying mixed fractions.